ES2213555T3 - PACKING SHEET WITH POSSIBILITY OF BEING CLOSED AGAIN AND PACKING WITH POSSIBILITY OF BEING CLOSED AGAIN THAT INCLUDES IT. - Google Patents

Abstract

Wrapping sheet (14,16) comprises an external primary layer (30), an internal layer (32) and a layer of permanent adhesive in between (34). A zone of the sheet (22) is heat-sealable. The main zone (36) of the sheet is gas-permeable apart from the zone around the seal, used to initiate the opening of the package. Independent claims are also included for the packages obtained with the wrapping sheet.

Description

Packing sheet with the possibility of being again closed and packaging with the possibility of being closed again than the incorporates

The present invention relates to a sheet of stratified packaging of the type comprising a primary layer associated with a weldable layer between which it is interposed, in at least one localized area, a layer of a permanent adhesive, presenting the aforementioned sheet in a localized area where the Permanent adhesive is present, a heat-welded region that allows heat sealing of the packaging and that allows Close the packaging again after an initial opening.

Currently, numerous food products, in Particularly fresh products are marketed packed in some bags or barquetas that are made essentially based on polymers

In order to allow conservation satisfactory of these foods, it is advantageous that the leaves of polymer, simple or complex, that enter the composition of the packaging, undergo a treatment that allows them to be made gas permeable. In particular, these treatments allow a control of the atmosphere inside the packaging, in articulate regulating the permeation of the gases generated by the product packed and in the opposite direction of the gases of the atmosphere outside through the sheet treated in this way. Leaf shape then a permeable membrane. The permeability conferred to the leaf generally refers to oxygen, carbon dioxide and water steam.

Several mechanical treatments of the sheets that allow to create a certain permeability to the gases As an example, these sheets can be perforated or even microperforated.

On the other hand, it is currently desirable that heat-sealed packaging, whether it be envelopes or boats, can be closed again so that only one fraction of the conditioned product in the packaging is consumed, the remaining fraction can be preserved with a view to its subsequent consumption

In particular, in order to allow a new closure of this type, it is known to use a shutter sheet comprising two layers of polymer between which it is interposed a layer of a permanent adhesive. The blade is welded on a support according to one of the layers to ensure the sealing of packing. At the time of opening the packaging, the layer welded is torn, leaving the adhesive to appear permanent that allows a new closing of the packaging.

In any case, it has been found that treatments that allow a non-permeable gas sheet can be applied to a sheet that allows an opening of the bag That can be closed again. Indeed, in this case, at the moment of the opening, and in particular of the rupture of the welded layer, the polymer sheet tends to tear, thus making a closure impossible back packing.

Document DE-76 17 442 U describes a bag formed by a packing sheet folded over herself. The packaging sheet has perforations only in its medium part and opposite lateral margins of the leaf destined to be soldiers are devoid of perforations.

Document FR-A- 2,741,605 describes a laminated packaging sheet comprising a layer primary associated with a weldable layer among which is interposed a layer of a permanent adhesive. This sheet of packaging, which corresponds to the preamble of claim 1, is suitable to ensure a new closure of the packaging after a initial opening

The object of the invention is to propose a sheet of packaging and packaging that contains it that allows packaging at the same time be opened and closed several times and that allow the circulation of gases between inside and outside of packing,

To this end, the invention has as its object a packaging sheet according to claim 1.

Particular embodiments are defined in the dependent claims.

The invention also relates to a packaging according to claim 4.

Finally, the invention relates to a bag packaging according to claim 5.

The invention will be better understood with reading of the description that follows, given by way of example only, and made referring to the drawings, in which:

- Figures 1 and 2 are respectively front and side elevation views of a packing bag according to the invention;

- Figure 3 is a view of a detail in section of the welded sealing area of the bag of the figure one;

- Figure 4 is a sectional view analogous to that of figure 3, taken after an initial opening of the bag;

- Figure 5 is a sectional view analogous to that of figures 3 and 4 after the new closure of the bag;

- Figure 6 is a perspective view of a packing boat whose access passage is sealed by a sheet stratified according to the invention;

- Figures 7 and 8 are partial views in section of the boat in figure 6 taken along the line VII-VII respectively before and after the opening; Y

- Figure 9 is a perspective view of a variant embodiment of a boat according to the invention.

The packaging 10 represented in figures 1 and 2 It is a bag intended for conditioning fresh products such like some legumes or some fruits. The bag consists of two rectangular main flexible sheets 14, 16 arranged one in front of the other and by a fund 18 constituted by a third flexible blade

The two main flexible sheets 14, 16 are joined to each other by heat welding following two edges Longitudinal 20A and 20B. The lower edge of the leaves 14, 16 is joined by a weld to the edge of the sheet 18 that forms the background.

Following its upper edge, the two sheets 14, 16 are joined to each other by a top weld 22 arranged transversely from one longitudinal edge to another. This welding It forms a means of opening and closing the packaging. This one is arranged at a distance from the upper edge of sheets 14 and 16, thus forming, beyond welding 22, two free areas 14A, 16A.

The two sheets 14, 16, 18 define between them a enclosure 24 in which the packaged products are contained.

As depicted in Figure 3, the sheets 14 and 16 that constitute the main faces of the bag 10 They have a stratified structure. These two sheets have for example the same structure.

Each comprises a primary layer 30 oriented towards the outside and a welding layer 32 oriented towards the inside of the bag. Between the primary layer 30 and the welding layer 32 is arranged a layer 34 of a permanent adhesive.

Longitudinal welding 22, performed between two facing faces of the welding layers 32, is a weld Meat to meat type. The two welding layers 32 are welded against each other by heat welding.

According to the invention, each of sheets 14 and 16 which constitute the main faces of the packaging presents, outside of the opening zone formed by the upper weld 22, a treatment that ensures gas permeability.

Thus, separated from weld 22, each sheet 14, 16 presents, in a predetermined area 36 that extends over the essential surface treatment that makes the sheet permeable to the gases This treated area 36 is represented by a frame of points on the figures.

The upper border 37 of zone 36 is separated from weld 22 by a band 38 left without treatment.

Welding 22 and border 37 extend in sensitively parallel to each other and are separated by a distance between 4 mm and 2 cm and preferably greater than 7 mm

The treated areas 36 extend over the entire width of sheets 14 and 16 from one longitudinal edge 20A to the other 20B. They extend from border 37 to the welding zone with the bottom 18.

As a variant, these areas are limited to some windows located on the part of sheets 14 and 16. In this case, to perform the treatment on the windows in question, it is you need to print some spots on the sheet for your location.

The treatment that makes gas permeable it consists, for example, in the realization of distributed perforations on the surface of zones 36.

Perforations are performed for example thanks to a mechanical installation comprising two cylinders that they revolve around parallel axes, these cylinders being in contact according to a tangency line. One of the cylinders is equipped on its surface with a drilling matrix made in general in metal. The other cylinder that forms a support surface It is generally made of a plastic material. The matrix of perforations penetrates the surface of the facing cylinder following the line of tangency. The film destined to form the sheets 14 and 16 of the bags circulates between the two cylinders and it it is thus drilled by a set of holes by removal of material.

As a variant of this drilling technique called rotary drilling, you can also use one or another of the two known procedures under the name of flame drilling and hot tip drilling.

The level of gas permeability is adjusted varying the density of the drilling organs, their size as well as the pressure applied between the two cylinders.

In order to perform perforations only in zones 36 and keeping the band 38 free of holes, the matrix drilling has an adapted profile and comprises in particular an area devoid of drilling organs. The zones provided with drilling organs form bands following all the contour of the cylinder that carries the matrix, or extend according to localized areas that extend following cylinder generatrices.

As a variant, the perforations are replaced by microperforations, formed without the removal of material and which form incisions in the material of sheets 14 and 16. These microperforations are obtained by the passage of each sheet between adjacent cylinders of which one comprises some blades or microblades capable of making an incision in the blade according to all its thickness.

According to a third variant, the permeability to the gases are obtained by performing microperforations with help of a discontinuous laser beam. Circulating the movie in continuous, a laser beam madly modifies the structure of the matter, thus creating micro-holes of a defined diameter and in particular between 100 and 200 µm. The level of permeability is adjusted by modifying the diameter of the micro holes and its density.

According to a fourth variant, a treatment that makes the sheet porous, giving it porosity.

This porosity is obtained thanks to two adjacent cylinders between which the leaf circulates, one being of the cylinders covered by a rough tank, which creates a weakening of the leaf. The level of permeability can be essentially adjusted by varying the pressure between the rollers of work.

According to a fifth variant, the permeability to gases is obtained by a treatment that makes it permeable as it  described in European patents No. 351,115 B1 and No. 351,116 B1.

To proceed with the opening of the bag, the operator takes in each hand an extension of sheets 14 and 16 which constitute the grab areas 14 A, 16 A located beyond the weld 22. Then separate the opposite skirts of the bag with a view to causing the opening of the bag. During traction of the two gripping areas in opposite directions, some are applied high forces on welding 22.

Under the action of these forces, the soldering layer 32 tears from side to side of weld 22.

Thus, as illustrated in Figure 4, the two sheets 14, 16 of the bag are then separated, comprising always one of them on the inside face a welded band 46 outlet of the weld layer 32 and the other sheet has a groove 48 corresponding to the footprint of the band 46.

The adhesive of layer 34 remains attached to the layer 30 at the bottom of slot 48 and / or remains supported by the welded strip 46 to form an adhesive coating 50 thereon as illustrated in figure 4.

It is conceived, as illustrated in Figure 5, that the approach of the two sheets and the relocation of the band welded 46 in slot 48 allows the closure of the packaging, by action of permanent adhesive coating 50 on the bottom 52 left clean of the groove.

At the time of opening, the opening area The packaging, formed by welding 22, opens without risk of complete tearing of one of the sheets 14, 16 since the weld 22 is arranged separately from zone 36 made permeable to the gases.

Indeed, the absence of the treatment that confers gas permeability in welding zone 22 avoid creating leaf tearing initiators in this area which is very requested at the time of opening, which avoids any risk of degradation of the leaves at the time of rupture of the weld layer 32.

The packaging 100, shown in Figure 6, it is constituted by a circular boat 112 and an operculum flexible shutter 114 of an access passage 116 inside the boat

The boat 112 is constituted by a layer of outer support of appropriate material, for example chloride polyvinyl, coated on its inner surface by a layer weldable, for example, from polyethylene.

The boat defines a receptacle 118 lined especially its contour by a flange 120 that delimits a flat welded surface of operculum 114, according to a weld circular 122.

Opercle 114 is stratified, that is made in several overlapping layers. For reasons of clarity, the layer thickness is exaggeratedly increased in the figures.

As depicted in Figure 7, the operculum 114 consists essentially of a support layer 124 and a weldable layer 126 with a permanent adhesive layer 128 interposed flat between them over the entire surface.

The support layer 124 comprises so advantageous impressions on its outer face. Can understand also a transparent layer that carries these prints counterbalanced on the outer surface of the support layer by middle of a layer of glue applied on your printed face.

The support layer 124 is, for example, a layer of 36 µm thick polyethylene terephthalate.

Permanent adhesive layer 128 is made by coating with the help of an adhesive mass initially in solution, in particular in aqueous dispersion. It can also be hot applied, in particular by extrusion.

A permanent adhesive, commonly designated under the name "hot melt" it suits this perfectly application. It is possible in particular to use Plastoflex 87.18 marketed by the Paramelt company in the Netherlands.

The thickness of the adhesive layer 128 is advantageously between 10 and 30 µm and in particular equal to about 20 µm.

Weldable layer 126 is for example a layer of polyethylene or polypropylene whose thickness is between 20 and 60 µm, and is in particular advantageously equal to 40 µm. Is layer is made of a material that allows a soldier with the facing layer of the boat 112.

As shown in Figure 6, the cord of peripheral welding 112 extends over the entire contour of the boat Ensures the tight seal of the boat. Because reasons of clarity, peripheral welding 122 has been marked with a plot in this figure.

The operculum 114 presents in the zone that clogs the step 116 a disc shaped zone 130 that has become permeable to the gases. This zone 130 extends away from the weld 122. Advantageously, the distance between weld 122 and zone 120 that has become permeable to gases is greater than 5 mm and by example equal to 7 mm.

Peripheral welding 122 is obtained by heat welded At the time of the soldier, the weldable layer of the cassette and weldable packing sheet 126 melt together, allowing to obtain, after cooling, a very weld reliable.

As illustrated in Figure 8, at the time of the opening of the packaging by traction of the edge of opercle 114 located in the vicinity of weld zone 122, the layer weldable 126 breaks.

Only one residual band 140 layer exit weldable 126 remains present on flange 120. It forms a welded cord Conversely, a groove 142 is formed in the layer weldable 126 operculum. The bottom of this slot is formed by permanent adhesive of layer 128.

As is known, the presence of the adhesive permanent on the surface facing the support layer 124 and possibly on welded bead 140 allows closing back of the packaging by replacing operculum 114.

Also in this embodiment, the limitation of the treatment that makes the area of gas permeable initiation of the opening of the packaging prevents this treatment favor full tearing of the operculum at the time of application of the necessary forces for the rupture of its layer weldable

For the manufacture of such packaging, the shutter sheet comes out of a band in which they have formed a succession of successive shutter sheets. These sheets are delimited each other by a visual reference point 150 arranged in one corner of each sheet. This reference point allows the correct positioning of each leaf on the wafer.

At the time of the treatment of the band, the treatment that makes the leaves locally gas permeable is carried out in areas positioned with respect to the points of successive reference 150.

Figure 9 shows a variant of realization of the packaging according to the invention.

This packaging 200 is constituted by a boat 200 sealed by an operculum 204 made from a sheet according to the invention. The operculum 204 is formed by three layers of the same nature as in the embodiment of the figures 6 to 8.

The barque 202 presents an accommodation cylindrical 208 which has in section the shape of a disk sector. This is intended to receive, for example, a portion of cheese.

The opening of the housing 206 is surrounded by a flange 208 comprising two main drying edges 210, 212, which extend parallel to the rectilinear edge of the sector of the disk that forms the housing 206. A rear edge 214 rectilinear extends perpendicular to the angle bisector bounded by edges 210 and 212.

Finally, the union between the edges 210, 212 and the rear edge 214 is secured by rectilinear sections parallel 216, 218 that extend laterally. These edges delimit some zones of opening of the packaging annotated with the references 220, 222. These areas extend in the corners defined between the leading edges 210,212, and the trailing edge 214.

These opening areas are located by the user using an adapted dial that invites the user to start The opening of the packaging in this area.

As in the preceding embodiment, the operculum 204 is welded according to a peripheral weld 224 on the flange contour 208.

The operculum 204 presents, in its median part defined between rectilinear sections 216, 218, an area 226 that is has made gas permeable by alignments 228 of perforations carried out continuously with the help of a laser beam, by example. These perforation lines 228 extend in parallel to the bisector the angle defined by the main edges 210, 212. Zone 226 extends separately from the welding sections 230, 232, which extend parallel to the edges 216, 218 in the opening areas 220, 222. The distance between these sections of welding 230, 232 and the extreme perforation lines 228 is by example equal to 7 mm.

The perforation lines 228 extend on the stretches of peripheral welding 224 that extend parallel to the main edges 210, 212 and the rear edge 214.

It is conceived that with such packaging, the opening being initiated in one of the zones 220, 222, one of the welded sections 230, 232, is initially released by rupture of the soldering layer. This break is made without tearing risks of the film, since no treatment that makes it permeable to Gases is present in this area.

At the time of the continuation of the opening of the packaging, the welding sections that extend along edges 210, 212 and 214 are released. Although the treated area is extends following these welding cords, the risk that the sheet tearing is very small, since the spread of the tearing of the weld layer is done following the length of these sections soldiers, so that only a little bit of force to cause tearing of the weldable film. Like this small force is not enough to initiate a complete tearing of the sheet despite the treatments that make the sheet permeable to gases

In this embodiment, operculum 204 is advantageously manufactured from a coil film, in the which perforation lines 222 are made following the film length This treatment is performed continuously by displacement of the film on an adapted equipment.

Claims (5)

1. Stratified packing sheet (14, 16; 204), of the type comprising a primary layer (30) associated with a weldable layer (32) between which a layer (34) is interposed in at least one localized area. of a permanent adhesive, said sheet having a localized area in which the permanent adhesive is present, a heat-sealing zone (22; 224) that allows thermal sealing of the packaging and allows a new closure of the packaging after a initial opening, characterized in that said sheet has at least one localized area (36; 228), a treatment that ensures gas permeability, in the place where each localized area treated (36; 228) extends outside the less a part of said heat-welding zone, each part (22; 224) of the heat-welding zone devoid of the treatment forming an area (22; 230, 232) initiating the opening of the packaging; and because the or each treated localized zone (36; 228) extends over the heat-welded zone (20A, 20B) outside the or each part (22) forming an initiation zone of the opening of the packaging. 2. Packing sheet according to claim 1, characterized in that the or each localized area treated (36; 228) has one of the treatments chosen in the group consisting of: perforations, microperforations, a mechanical treatment that makes it porous, and localized holes made with laser. 3. Packing sheet according to claim 1 or 2, characterized in that the minimum distance between the border (37) of the or each treated localized area (36; 228) and the or each part (22; 224) of the heat-welded zone It is devoid of treatment is greater than 7 mm. 4. Packaging comprising an external wall that delimits a housing provided with an access passage to said housing, characterized in that said passage is sealed by a laminated sheet according to any of the preceding claims, which sheet is thermally welded onto said wall. external at the periphery of the passage following its weldable layer in said heat-welding zone, the welded part or part of the heat-welded zone devoid of treatment forming a zone (230; 232) for initiating the opening of the packaging. 5. Packaging bag comprising at least one wall delimited by a sheet according to any of claims 1 to 3, characterized in that said sheet (14, 16) is thermally welded against another wall (16, 14) of the bag following its weldable layer (32) in said heat welding zone (22), the or each welded part (22) of the heat welding zone devoid of treatment forming an initiation zone of the opening of the packaging.